CN111408806B

CN111408806B - Welding device and welding method

Info

Publication number: CN111408806B
Application number: CN202010092641.XA
Authority: CN
Inventors: 桥本升; 笠间隆博
Original assignee: Senju Metal Industry Co Ltd
Current assignee: Senju Metal Industry Co Ltd
Priority date: 2019-04-22
Filing date: 2020-02-14
Publication date: 2021-09-24
Anticipated expiration: 2040-02-14
Also published as: US11059119B2; JP6590232B1; MY196849A; JP2020178086A; CN111408806A; US20200331086A1

Abstract

The invention aims to provide a welding device and a welding method which are more difficult to adhere scum to a substrate than the prior art. A welding device (100) according to the present invention comprises: a cavity (120) which contains solder and has an opening (122) for discharging the solder on the bottom surface or the side surface; a pump (140) for feeding solder to the cavity (120); and an inner groove (160) which communicates with the opening (120) and is welded by solder supplied from the opening (120).

Description

Welding device and welding method

Technical Field

The present invention relates to a welding apparatus and a welding method.

Background

When soldering an electronic component to a circuit board, a soldering apparatus is used. Among soldering apparatuses, there are reflow soldering apparatuses and flow soldering apparatuses, and as the flow soldering apparatuses, a jet soldering apparatus, a dip soldering apparatus, and the like are known. The jet welding apparatus includes a solder bath for containing molten solder, a jet nozzle provided inside the solder bath, and a pump. Then, the pump delivers the solder contained in the solder bath to the jet nozzle. Then, the solder is ejected from the jet nozzle. At this time, the jet welding apparatus passes the substrate over the molten solder jetted from the jet nozzle. Thus, the jet welding apparatus performs welding on the substrate. The solder jetted from the jet nozzle drops toward the solder bath and is supplied again to the pump. That is, the jet welding apparatus performs welding on a substrate by using solder circulating inside the apparatus. The dip soldering apparatus includes a solder tank for containing molten solder. The lower surface of the substrate is immersed in the liquid surface of the solder contained therein. Thus, the dip soldering apparatus performs soldering on the substrate.

In this way, the jet welding apparatus and the dip welding apparatus weld the substrates, but the molten high-temperature solder comes into contact with air in the welding step. Then, the high-temperature solder is brought into contact with air, and the solder reacts with oxygen. The solder reacts with oxygen to generate an oxide of the solder (dross). Therefore, in the jet welding apparatus and the dip welding apparatus, since the dross contains the solder used for welding, there is a risk that the dross adheres to the substrate. When the dross adheres to the substrate, the appearance of the substrate itself deteriorates, and the commercial value of the soldered substrate is lowered. In addition, when a large amount of dross adheres to the substrate, short-circuiting may occur between adjacent solder portions, and insulation resistance may decrease. Therefore, in the flow-type soldering apparatus, a solder bath having a structure that suppresses adhesion of dross to the substrate may be used.

For example, patent document 1 describes a jet solder bath having a structure that suppresses adhesion of scum to a substrate. The jet solder bath described in patent document 1 includes a jet pump and a jet nozzle in a main body. The body is divided into an upper chamber and a lower chamber by a bottom plate, and a jet nozzle and a jet pump are provided in the bottom plate. Then, if the solder is pressure-fed from the upper chamber to the lower chamber by the discharge pump, the solder is spouted from the spout nozzle to the upper chamber side through the lower chamber. Then, the printed circuit board is brought into contact with the wave jetted from the jet nozzle, whereby the welded portion of the printed circuit board is welded.

In the jet solder bath disclosed in patent document 1, the upper chamber is separated into a nozzle side and a pump side by a partition plate. The upper part of the partition plate protrudes from the liquid surface, and the lower part of the partition plate is submerged below the liquid surface. In addition, the oxide (dross) floats near the surface of the molten solder because it has a lower specific gravity than the molten solder. Therefore, the oxide (dross) floating on the liquid surface is prevented from moving from the nozzle side to the pump side by the partition plate. That is, in this jet solder bath, the oxide (scum) on the nozzle side is not moved from the nozzle side to the pump side, and is sucked into the jet pump. That is, in the jet solder bath described in patent document 1, oxides (scum) on the nozzle side are less likely to adhere to the substrate.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-353719.

Disclosure of Invention

Problems to be solved by the invention

As described above, the jet solder bath disclosed in patent document 1 includes a partition plate to prevent the movement of the dross (oxide) from the nozzle side to the pump side. Therefore, in the upper chamber, the scum is difficult to move from the nozzle side toward the pump side. However, on the nozzle side, relatively large dross (dross with four sides of about 1.5 cm) and powdery small dross (dross with a diameter of 1 mm or less) are generated. The small dross is easily affected by the flow, and is caught by the flow of the solder jetted from the jet nozzle and passes through the lower portion of the partition plate, so that not less of the small dross moves toward the pump side. Therefore, as time passes, a small amount of scum may accumulate on the liquid surface on the pump side.

In the jet solder bath described in patent document 1, a solder liquid surface is also formed on the pump side. The shaft connected to the screw of the jet pump is connected to the screw for feeding molten solder in the solder liquid under pressure via the liquid surface. By the rotation of the shaft, a small amount of atmospheric air is drawn into the solder liquid surface around the rotation shaft. This also generates a small amount of scum on the pump side, and the small amount of scum may accumulate on the liquid surface on the pump side.

In addition, when dross is present on the pump-side solder surface, there is a risk that the dross is sucked together with the molten solder by the jet pump. That is, the dross is spouted from the spout nozzle together with the molten solder and may adhere to the substrate.

In view of the above-described problems, an object of the present invention is to provide a soldering apparatus and a soldering method which make it difficult for dross to adhere to a substrate as compared with the conventional one.

Means for solving the problems

(mode 1)

The welding device according to embodiment 1 includes: a cavity for accommodating solder and having an opening portion for discharging the solder on a bottom surface or a side surface; a pump for feeding the solder to the cavity; and an inner groove which communicates with the opening and is welded by solder supplied from the opening.

When dross is contained in solder, the dross floats on the upper portion of the solder and is located near the liquid level of the solder because the dross has a lower specific gravity than the solder. Therefore, in the soldering apparatus according to the aspect 1, when the solder containing dross is accommodated in the cavity, the dross is located near the surface of the solder in the cavity. The opening for discharging the solder is located on the bottom surface or the side surface of the cavity. Thus, by adjusting the height of the liquid level of the solder in the cavity to a position away from the opening, it is possible to suppress the passage of dross floating near the liquid level through the opening. Therefore, the soldering apparatus can supply the solder containing little dross to the inner tank, and as a result, the dross can be made hard to adhere to the substrate.

(mode 2)

According to the welding device of the aspect 2, in the welding device of the aspect 1, the opening is located on a bottom surface of the cavity.

In the welding device according to mode 2, the opening is located on the bottom surface on the lower side of the side surface in the direction of gravity. Therefore, the opening is positioned farther from the liquid surface than in the case of the side surface. That is, the dross is more difficult to pass through the opening. Therefore, this soldering apparatus makes it difficult for dross to adhere to the substrate, as compared with the soldering apparatus according to embodiment 1.

(mode 3)

According to the soldering apparatus related to the aspect 3, in the soldering apparatus according to the aspect 1 or the aspect 2, the pump conveys the solder from the lower side to the upper side in the direction of gravity.

When the pump conveys solder from the upper side to the lower side in the direction of gravity, the pump sucks the solder from the upper side. That is, the pump easily sucks dross located near the solder level. Therefore, the pump may suck in more dross while sucking in the solder. Also, if the pump sucks in dross, the pump cannot convey solder corresponding to the amount of sucked dross. That is, since the amount of solder that the pump can deliver is reduced, the delivery efficiency may be reduced.

Also, if the pump delivers more dross to the chamber, the density of the dross in the chamber increases. In this case, the dross easily passes through the opening in the chamber.

However, in the soldering apparatus according to embodiment 3, the pump conveys solder from the lower side to the upper side in the direction of gravity. That is, the pump sucks the solder from a position away from the liquid surface. Therefore, the pump is difficult to suck the scum, and the conveying efficiency of the pump is difficult to reduce. In addition, in this welding apparatus, since the pump is hard to suck up dross, an increase in the density of dross in the cavity can be suppressed. As a result, the amount of scum passing through the opening can be reduced, and scum can be prevented from adhering to the substrate.

(mode 4)

According to the welding device of the aspect 4, in the welding device according to any one of the aspects 1 to 3, the pump is a screw pump.

According to the soldering apparatus of the aspect 4, the structure of the aspect 3 in which the solder is fed from the lower side to the upper side in the direction of gravity can be realized by the screw pump.

(mode 5)

According to the welding device of the aspect 5, in the welding device according to any one of the aspects 1 to 4, the chamber has a vent hole communicating with the atmosphere.

In the soldering apparatus according to the aspect 5, if the cavity does not have the vent, the solder supplied to the cavity by the pump is pressure-fed from the opening by the pressure generated by the pump. Therefore, the dross located near the solder liquid level in the cavity is pushed by the pressure generated by the pump and flows, and the possibility of passing through the opening is increased.

However, the cavity of the welding apparatus according to the embodiment 5 has a vent. Thus, the solder supplied to the cavity by the pump is temporarily stored in the cavity. Then, as the solder in the cavity increases, the pressure at the opening of the cavity increases, and the solder is pressure-fed from the opening by the increased pressure. That is, the dross located near the solder liquid level in the cavity is not pumped toward the opening by the pressure of the pump. Therefore, since the welding apparatus according to the embodiment 5 has the vent, passage of dross through the opening is suppressed.

(mode 6)

According to the welding device of the aspect 6, in the welding device according to any one of the aspects 1 to 5, the inner groove accommodates the solder, and has a discharge hole for discharging the accommodated solder on a bottom surface.

According to the soldering apparatus of the aspect 6, the solder supplied from the cavity and accommodated in the inner tank is discharged from the discharge hole of the inner tank. Thus, the inner tank contains a large amount of solder containing little dross, which is just supplied from the cavity. Therefore, the welding device can perform welding with the solder containing little dross in the inner tank, and can prevent welding with the solder generating dross.

(mode 7)

The welding device according to aspect 7 is the welding device according to aspect 6, further including: an outer tank; a bottom plate which separates the interior of the outer tank into an outer tank upper portion and an outer tank lower portion for receiving the solder discharged from the discharge hole, and which has a solder introduction port for connecting the outer tank upper portion and the outer tank lower portion, an inner tank connection port for communicating with the inner tank, a cavity connection port for communicating with the cavity, and an opening connection port for communicating with the opening; and a shielding plate for separating the lower part of the outer tank into: and a second lower portion having a flow path from the opening connection port to the inner tank connection port, wherein the pump conveys solder from the first lower portion to the cavity.

In the welding apparatus according to mode 7, the solder discharged from the discharge hole of the inner tank is supplied to the upper portion of the outer tank. The solder on the upper portion of the outer tank moves from the solder introduction port to the first lower portion by gravity. Then, the solder in the first lower portion is transferred to the cavity by a pump. Then, the solder in the cavity is supplied to the inner groove through the opening, the opening connection port, the second lower portion, and the inner groove connection port in this order. Thereafter, the solder contained in the inner tank is discharged from the discharge hole of the inner tank and supplied again to the upper portion of the outer tank. As described above, in the soldering apparatus according to embodiment 7, the solder can be circulated inside the apparatus, and the solder can be convected. In addition, the soldering device can make the soldering temperature in the device uniform through the convection of the soldering tin, and can supply the soldering tin with stable temperature to the inner groove. That is, the solder of the inner tank can be stabilized at the optimum temperature for the welding. Therefore, the welding apparatus can perform welding at a temperature optimal for welding.

(mode 8)

The welding method according to embodiment 8 includes: a step of discharging the solder from an opening part provided on a bottom surface or a side surface of a cavity for accommodating the solder; a step of delivering the solder to the cavity by a pump; and a step of welding the inner tank communicating with the opening with the solder supplied from the opening.

In the welding method according to mode 8, when the solder containing dross is accommodated in the cavity, the dross is located near the surface of the solder in the cavity. The opening for discharging the solder is located on the bottom surface or the side surface. Therefore, as in the case of embodiment 1, it is difficult for the dross to pass through the opening together with the solder, and it is difficult for the dross to pass through the opening. Therefore, the welding method can supply the solder containing little dross to the inner tank. In addition, the soldering method can perform soldering using the solder. That is, this soldering method makes it difficult for dross to adhere to the substrate.

Effects of the invention

According to the present invention, scum is less likely to adhere to a substrate than in the prior art.

Drawings

Fig. 1 is a sectional perspective view of a welding apparatus according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the welding device shown in FIG. 1;

FIG. 3 is a plan view of the welding apparatus shown in FIG. 1;

fig. 4 is a sectional view of the inner tank at the time of welding in the welding apparatus shown in fig. 1.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and redundant description thereof is omitted.

[ first embodiment ]

< constitution >

Fig. 1 is a sectional perspective view of a welding apparatus according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view of the welding device shown in fig. 1. Fig. 3 is a plan view of the welding apparatus shown in fig. 1.

Referring to fig. 1, welding apparatus 100 includes chamber 120, pump 140 (see fig. 2), inner tank 160, solder blowout part 180, outer tank 200, bottom plate 220, and shielding plate 240. As an example, the soldering apparatus 100 is a cyclic dip soldering apparatus (see fig. 4) for soldering the electronic component 320 to the substrate 300. In fig. 1, the pump 140 is omitted to ensure easy visibility.

Hereinafter, each component of welding apparatus 100 will be described with reference to fig. 2.

For example, the cavity 120 is a cuboid box-shaped container for accommodating solder. In addition, the cavity 120 has an opening 122 for discharging solder, an intake port 124, and a vent 126 communicating with the atmosphere, for example. For example, the opening 122 and the suction port 124 are located on the bottom surface of the chamber 120. In addition, as an example, the vent 126 is located on the upper surface of the cavity 120.

For example, the pump 140 is a screw pump. For example, the pump 140 has a function of feeding solder from the lower side toward the upper side in the gravity direction, and sucks the solder from the suction port 124. Thus, the pump 140 can deliver solder from the first lower portion 206 to the cavity 120. More specifically, the pump 140 includes a cylinder 142, a screw 144, a shaft 146, a shaft pulley 148, a belt 150, a motor 152, and a motor pulley 154. The cylinder 142 is a cylindrical block provided with a hole, and is provided on the bottom surface of the chamber 120. A screw 144 is disposed in a bore of the cylinder 142, and a shaft 146 is fixed to the screw 144. The shaft 146 extends in the direction of gravity, and a shaft pulley 148 is attached to an upper portion of the shaft 146. Further, the shaft pulley 148 and the motor pulley 154 are coupled via a belt 150. Therefore, the shaft pulley 148 rotates in conjunction with the rotation of the motor 152. The motor 152 is mounted to a wall surface of the outer tub 200.

The outer tub 200 is, for example, a box-shaped container having a cubic shape, and houses the cavity 120, the inner tub 160, and the solder blowout part 180. The upper part of the outer tub 200 is open.

The bottom plate 200 separates the interior of the outer tank 200 into an outer tank upper portion 202 and an outer tank lower portion 204. Further, the bottom plate 220 has two solder introduction ports 222 (see fig. 3) that connect the outer tank upper portion 202 and the outer tank lower portion 204, an inner tank connection port 224 that communicates with the inner tank 160, a chamber connection port 226 that communicates with the chamber 120, and an opening connection port 228 that communicates with the opening 122.

The shield 240 separates the outer tank lower portion 204 into the first lower portion 206 and the second lower portion 208. At the position of the first lower portion 206 of the bottom plate 220, a solder introduction port 222 (see fig. 3) and a cavity connection port 226 are provided. Thus, the solder flowing from the solder introduction port 222 toward the first lower portion 206 can flow out from the cavity connection port 226. In other words, the first lower portion 206 has a flow path from the solder introduction port 222 to the cavity connection port 226. On the other hand, an opening connection port 228 and an inner tank connection port 224 are provided at the second lower portion 208 of the bottom plate 220. Thus, the solder flowing into the second lower portion 208 from the opening connection port 228 can flow out from the inner groove connection port 224. In other words, the second lower portion 208 has a flow path from the opening connection port 228 to the inner tank connection port 224.

The solder blowout part 180 is a cylindrical body having a quadrangular cross section and is mounted on the bottom plate 220. The solder blowout part 180 connects the inner groove connection opening 224 and the inner groove 160. Thus, the solder blowout part 180 forms a flow path from the inner tank connection port 224 to the inner tank 160.

For example, the inner tub 160 is a box-shaped container having a cubic shape. The inner groove 160 communicates with the opening 122 via the opening connecting opening 228, the second lower portion 208, the inner groove connecting opening 224, and the solder blowout part 180. Therefore, the solder flowing out of the opening 122 is supplied to the inner groove 160. The inner groove 160 can then accommodate the solder. In addition, for example, solder is filled between the opening 122 and the inner groove 160, and the solder does not contact air during this period. The solder contained in the inner tank 160 forms a liquid level L2. The upper side of the inner tub 160 is opened to receive the substrate 300 and the tray 102 (see fig. 4) which are transferred during soldering. The bonding apparatus 100 can bond the substrate 300 by immersing the lower surface of the substrate 300 in the liquid level L2 in the inner tank 160. That is, the inner groove 160 has a function of welding by solder supplied from the opening 122. The welding operation of welding apparatus 100 will be described later. The inner groove 160 has two discharge holes 162 (see fig. 3) for discharging the solder stored in the bottom surface. For example, the discharge hole 162 is a slit. Since the inner tank 160 is accommodated in the outer tank 200, the solder discharged from the discharge holes 162 (see fig. 3) of the inner tank 160 moves toward the outer tank upper portion 202. That is, the outer tub upper 202 can receive the solder discharged from the discharge hole 162.

< action >

Next, an operation of welding apparatus 100 for circulating molten solder and a welding operation of welding apparatus 100 will be described.

(operation of welding apparatus 100 circulating molten solder)

Referring to fig. 2, an operation of welding apparatus 100 for circulating molten solder will be described. When the welding apparatus 100 circulates the molten solder, first, the welding apparatus 100 rotates the motor 152. Thereby, the screw 144 rotates, and the pump 140 conveys the solder of the first lower portion 206 toward the inside of the cavity 120. Then, the solder in the cavity 120 increases, and the height of the liquid level L1 of the solder in the cavity 120 rises. Therefore, the pressure of the opening 122 increases as the solder in the cavity 120 increases. Then, the solder is pressure-fed from the opening 122 in accordance with the increased pressure. At this time, the liquid level L1 in the chamber 120 and the liquid level L2 in the inner tank 160 are both in communication with the atmosphere. Therefore, the height of the liquid level L2 rises until it becomes the same as the height of the liquid level L1. That is, the solder in the cavity 120 is supplied to the inner groove 160 by driving of the pump 140, and is stored in the inner groove 160. Thereafter, the solder contained in the inner tank 160 is discharged from the discharge hole 162 (see fig. 3) of the inner tank 160 and moves toward the outer tank upper portion 202. The outer bin upper portion 202 then receives the drained solder. At this time, the position of the solder liquid level L3 of the outer tank upper part 202 is set to be higher than the position of the discharge hole 162. That is, the discharge hole 162 is positioned inside the solder liquid. Thereafter, the solder passes through the outer tank upper portion 202 and moves toward the solder introduction port 222 (see fig. 3) located on the bottom plate 220. Then, the solder of the outer tub upper portion 202 is supplied from the solder introduction port 222 to the first lower portion 206. After that, the solder accumulated in the first lower portion 206 is again transferred to the cavity 120 by the pump 140. In this way, in the welding apparatus 100, the solder circulates inside.

(welding operation of welding apparatus 100)

Next, the welding operation of welding apparatus 100 will be described with reference to fig. 4. Fig. 4 is a sectional view of inner tank 160 during welding in welding apparatus 100 shown in fig. 1. During soldering, the substrate 300 is transported to the inner tank 160 by an existing transport device (not shown) while being placed on the tray 102. The tray 102 has through openings 104 formed therein so as to correspond to the soldering portions 340 of the substrate 300. Therefore, if the tray 102 is conveyed toward the inside of the inner groove 160, the soldering portion 340 of the substrate 300 is in contact with the solder via the through opening 104. Thus, in the soldering apparatus 100, the soldering portion 340 of the substrate 300 is soldered. The tray 102 is provided with a plurality of recesses 106 and a cover 108 corresponding to the arrangement of the electronic components 320 on the substrate 300. This prevents the tray 102 from coming into contact with solder except for the solder portion 340 of the substrate 300. In this manner, the soldering apparatus 100 performs soldering of the substrate 300 by using the tray 102. That is, the welding apparatus 100 can perform so-called solder resist tray welding.

< action and Effect >

Next, the operation and effect of welding apparatus 100 will be described.

(first Effect)

As described above, the dross has a lower specific gravity than the solder and floats near the surface of the solder. Therefore, the dross in the chamber 120 is located near the liquid level L1 (see fig. 2). The opening 122 for discharging solder is located on the bottom surface of the cavity 120. That is, the opening 122 is positioned away from the liquid level L1. Therefore, in order to pass the dross through the opening 122, the dross needs to be once sunk from the vicinity of the solder liquid level L1 to a position distant from the liquid level L1 where the opening 122 is located. That is, in the soldering apparatus 100, the dross is hard to pass through the opening 122 together with the solder and hard to pass through the opening 122. Therefore, the welding apparatus 100 can supply the solder containing little dross to the inner tank 160. The welding apparatus 100 can perform welding in the inner tank 160 by using the solder. That is, the soldering apparatus 100 makes it difficult for dross to adhere to the substrate 300.

(second Effect)

The second effect is an effect of the welding apparatus 100 including the pump 140 that conveys solder from the lower side to the upper side in the direction of gravity.

Unlike the soldering apparatus 100, when the pump conveys solder from the upper side toward the lower side in the direction of gravity, the pump sucks the solder from the upper side. That is, the pump easily sucks dross located near the solder level. Therefore, the pump may suck in more dross while sucking in the solder. Also, if the pump sucks in dross, the pump cannot convey solder corresponding to the amount of sucked dross. That is, since the amount of solder that the pump can deliver is reduced, the delivery efficiency may be reduced.

Also, if the pump delivers more dross to the chamber, the density of the dross in the chamber increases. In this case, the dross easily passes through the opening 122 in the chamber.

However, in the soldering apparatus 100, the pump 140 conveys solder from the lower side to the upper side in the direction of gravity. That is, the pump 140 sucks the solder from a position away from the liquid surface. Therefore, in the welding apparatus 100, since the pump 140 hardly sucks the dross, the lowering of the conveying efficiency of the pump 140 can be suppressed. In the welding apparatus 100, since the pump 140 is hard to suck up dross, an increase in the density of dross in the cavity 120 can be suppressed. As a result, the amount of scum passing through the opening 122 can be reduced, and scum can be prevented from adhering to the substrate 300.

(third Effect)

In the soldering apparatus 100, if the cavity 120 does not have the vent 126, the solder supplied to the cavity 120 by the pump 140 is pressure-fed from the opening 122 by the pressure generated by the pump 140. Therefore, the dross located near the solder level in the cavity 120 is pushed by the pressure generated by the pump 140 and flows, and the possibility of passing through the opening 122 is increased.

However, the cavity 120 of the welding device 100 has a vent 126. Thereby, the solder supplied to the cavity 120 by the pump 140 is temporarily accumulated in the cavity 120. Then, as the solder in the cavity 120 increases, the pressure in the opening 122 increases, and the solder is pressure-fed from the opening 122 by the increased pressure. That is, the dross located near the solder level L1 in the cavity 120 is not pressure-fed to the opening 122 by the pressure of the pump 140. Therefore, since the welding apparatus 100 has the vent hole 126, passage of dross through the opening 122 is suppressed.

(fourth Effect)

In addition, when the liquid is pumped by the pump, the pressure applied to the liquid by the pump may fluctuate slightly, and waves may be formed in the pumped liquid. In particular, when the pump is rotated at a high speed, a large wave is formed in the liquid to be pumped. Therefore, when the solder is supplied to the groove by the pump directly connected to the groove, the liquid level of the solder stored in the groove may fluctuate.

In the welding apparatus 100, a chamber 120 having a vent 126 is provided on the downstream side of the pump 140. Therefore, the solder supplied to the cavity 120 by the pump 140 forms a wave due to a subtle pressure fluctuation of the pump 140 at the solder liquid level L1 of the cavity 120. However, the pressure corresponding to the height of the solder liquid level L1 is uniformly applied to the solder in the opening 122 by the pascal principle. Thus, the solder pumped from the opening 122 becomes a stable flow with less turbulence, and is supplied from the solder blowout part 180 to the inner groove 160. That is, the soldering apparatus 100 can suppress the wave of the solder liquid level L2 in the inner tank 160.

(fifth Effect)

The inner groove 160 has a discharge hole 162 (see fig. 3) for accommodating solder and discharging the solder accommodated in the bottom surface. Thereby, the solder supplied from the cavity 120 and accommodated in the inner groove 160 is discharged from the discharge hole 162 of the inner groove 160. Accordingly, the inner tub 160 contains a large amount of solder containing little dross, which is just supplied from the cavity 120. Therefore, the welding apparatus 100 can perform welding with solder containing little dross in the inner tank 160, and can prevent welding with solder in which dross is generated.

(sixth Effect)

As described above, in the welding apparatus 100, the solder circulates inside the welding apparatus 100. Thereby, the solder is convected. The soldering apparatus 100 can make the solder temperature in the apparatus uniform by convection of the solder, and can supply the solder of a stable temperature to the inner tank 160. That is, the solder of the inner groove 160 can be stabilized at the optimum temperature for the welding. Therefore, the welding apparatus 100 can perform welding at a temperature optimal for welding.

(seventh Effect)

Further, when the molten solder circulates through the soldering apparatus 100, the discharge hole 162 is positioned inside the solder liquid.

Thus, in the welding apparatus 100, the solder can move from the inner tank 160 to the outer tank upper portion 202 without contacting the atmosphere. That is, in the welding apparatus 100, the solder can be prevented from being oxidized without contacting the solder with the atmosphere while the solder moves from the inner tank 160 to the outer tank upper portion 202.

< modification example >

Next, a modification of welding apparatus 100 will be described.

(first modification)

In the welding apparatus 100, the cavity 120 has an opening 122 in the bottom surface. However, the cavity 120 may have the opening 122 on the side surface. This is because dross floats near the liquid level L1, and therefore even when the opening 122 is located on the side, if the opening 122 is located away from the liquid level L1, the welding apparatus 100 can prevent dross from passing through the opening 122. The opening 122 needs to be located below the solder liquid level L1 in the cavity 120, and is preferably located near the bottom surface of the cavity 120.

(second modification)

In addition, the pump 140 may not be a screw pump. The pump 140 may be a pump such as a vane pump that can feed solder. This is because the soldering apparatus 100 can supply solder to the inner tank 160 if the pump 140 can feed solder to the cavity 120.

(third modification)

Additionally, the chamber 120 may also be devoid of vents 126. In the case where the chamber 120 does not have the vent hole 126, as described above, the risk of the dross in the chamber 120 being pressure-fed from the opening 122 by the pressure generated by the pump 140 increases. However, since the opening 122 is located at the bottom, the dross located near the liquid level L1 is still difficult to flow out through the opening 122.

(fourth modification)

The welding apparatus 100 is a circulating immersion type welding apparatus that performs welding using a tray 102. However, welding apparatus 100 may also be a jet welding apparatus. In this case, in welding apparatus 100, inner tank 160 includes a jet nozzle that jets the solder supplied from opening 122. Thus, welding apparatus 100 can perform jet welding using a jet flow from the jet nozzle.

(fifth modification)

Further, welding apparatus 100 may be a partial welding apparatus. In this case, in the welding apparatus 100, the inner tank 160 includes a solder jet nozzle that jets solder to a necessary region. Thus, the solder jet nozzle can jet solder locally to the member to be welded. That is, welding apparatus 100 can perform local welding using the jet solder nozzle.

(sixth modification)

The discharge hole 162 is a slit. However, the discharge hole 162 may be an opening of any shape, such as a circle or a polygon. This is because even when the outlet 162 has an opening of such a shape, the outlet 162 can discharge the solder contained in the inner groove 160.

While the embodiments of the present invention and the modifications thereof have been described above, it is needless to say that the above-described examples are only for the purpose of facilitating understanding of the present invention and do not limit the present invention. The present invention can be modified and improved as appropriate without departing from the scope of the invention, and equivalents thereof are also included in the present invention. In addition, any combination or omission of the respective constituent elements described in the claims and the description may be made within a range in which at least part of the above-described problems can be solved or at least part of the effects can be achieved.

Description of the symbols

100 welding device

102 tray

120 chamber

122 opening part

124 suction inlet

126 vent opening

140 pump

160 inner tank

162 discharge hole

180 solder blowout part

200 outer groove

202 upper part of outer groove

204 lower part of the outer groove

206 first lower part

208 second lower part

220 bottom plate

222 solder introducing port

224 inner groove connecting port

226 cavity junction

228 opening connecting port

240 shield plate

300 base plate

320 electronic component

340 welding part

L1 liquid level

L2 liquid level

L3 liquid level.

Claims

1. A welding device is provided with:

a cavity for accommodating solder and having an opening portion for discharging the solder on a bottom surface;

a pump that conveys solder toward the cavity; and

an inner tank communicating with the opening and welded by solder supplied from the opening,

the inner groove accommodates solder, and has a drain hole in a bottom surface thereof for draining the solder accommodated therein.

2. The welding device of claim 1 wherein the opening is at a bottom surface of the cavity.

3. The soldering apparatus according to claim 1 or claim 2, wherein the pump conveys the solder from a lower side to an upper side in a direction of gravity.

4. The welding device of claim 1 or claim 2, wherein the pump is a screw pump.

5. The welding device according to claim 1 or claim 2 wherein the cavity has a vent in communication with the atmosphere.

6. The welding device according to claim 1 or claim 2, further comprising:

an outer tank;

a bottom plate that separates the inside of the outer tank into an outer tank upper portion and an outer tank lower portion that receive solder discharged from the discharge hole, and that has a solder introduction port that connects the outer tank upper portion and the outer tank lower portion, an inner tank connection port that communicates with the inner tank, a cavity connection port that communicates with the cavity, and an opening portion connection port that communicates with the opening portion; and

a shield plate separating the lower part of the outer tank into: a first lower portion having a flow path from the solder introduction port to the cavity connection port, and a second lower portion having a flow path from the opening connection port to the inner groove connection port,

wherein the pump delivers solder from the first lower portion towards the cavity.

7. A welding method, comprising:

a step of discharging the solder from an opening part provided on a bottom surface of a cavity for accommodating the solder;

a step of delivering solder to the cavity by a pump;

welding an inner groove communicating with the opening with solder supplied from the opening; and

and a step of discharging the solder contained in the inner groove from a discharge hole located on the bottom surface.